Background & objective: Hepatic metastases are common for patients with malignant tumors, especially for the gastrointestinal malignancies. Early diagnosis confers better prognosis. This study was designed to investigate the hepatic hemodynamic changes by multi-slice helical perfusion CT in rats with liver micrometastatases of Walker-256 tumor cells.
Methods: Liver micrometastatases were produced in 22 SD rats by injecting 2 x 10(7) Walker-256 cells into the spleens. The ten experimental control rats were injected with normal saline solution. Ten rats were randomized into empty self control group from the experimental group before injecting tumor cells, which were studied by CT perfusion technique before being injected tumor cells. The time-density curves of the aorta, portal vein, and liver were used to calculate liver perfusion parameters by gradient method designed for the dual blood supply. These liver perfusion parameters were hepatic arterial perfusion (HAP), portal vein perfusion (PVP), hepatic perfusion index (HPI) and total hepatic blood flow. All the parameters were compared between the groups. H&E staining method was used to confirm the micrometastases pathologically.
Results: In the experimental group, 19 rats were found with micrometastases, of which the diameter was 0.5 mm to 6.6 mm. HAP was (97.67+/-31.42) ml x min(-1) x (100 ml) (-1) in metastasis group, and (43.35+/-17.39)ml x min(-1) x (100 ml) (-1) in control group, and (40.77+/-18.91) ml x min(-1) x (100 ml) (-1) in empty self control group. PVP was (295.49+/-61.85) ml x min(-1) x (100 ml) (-1) in metastasis group, and (385.7+/-71.25) ml x min(-1) x (100 ml) (-1) in control group, and (362.73+/-78.56) ml x min(-1) x (100 ml) (-1) in empty self control group, It was found that the HAP was higher in the rats with micrometastases than in those of the empty control group and also those of control group (F=47.84, P<0.000,1). While the PVP was lower in the rats with micrometastases than in those of the two control groups (F=14.10, P<0.000,1). For the total hepatic blood flow, no significant difference was found among the three groups (F=1.39, P=0.255).
Conclusion: Higher HAP and lower PVP was noted in the rats with micrometastases. Perfusion CT technique can be used to evaluate the hepatic hemodynamic changes and thus has a potential clinical value for early diagnosis of liver micrometastases.